It is known to use a basepad extension on a removable ammunition magazine, particularity for handguns, in order to increase the capacity of the magazine and/or to provide a handgrip portion that will extend beyond the handgun grip when installed. This allows better hand grasp on the magazine for rapid removal and insertion of magazines.
The OEM handgun magazine typically includes a tubular body with an open bottom end with a flange or rim extending from two or three edges of the open end. A standard baseplate or basepad typically is attached to the magazine body by sliding over this flanged rim. It is held in place either by an internal engagement pushed against the basepad by the magazine's spring or by another mechanical locking means. In many common handgun magazines, such as for the Glock™ pistol, the magazine body is made of a polymer material (or combination of polymer and steel), while the basepad extension is typically made of lightweight metal, such as an aluminum alloy. Many extended basepads include an integral floor or bottom wall that defines a closed cavity to receive the lower end of a follower spring. To remove the follower spring or access the interior of the magazine tube, the extended basepad must be removed from the magazine tube. These often require compression of the magazine's spring as the basepad extension is slid into an engagement with the magazine body. This can require a challenging level of manual dexterity or can result in damage to the magazine's spring as the basepad is slid into position orthogonal to the force of the spring.
Some engagement mechanisms utilize a metal pin, which concentrates force against a single point at the bottom end of the magazine tube. This can lead to the magazine tube deforming when dropped on a hard surface. When this happens, the basepad body disengages from the magazine body, often scattering the loaded rounds contained within the magazine. Other designs have complex assembly mechanisms or require the use of a tool for assembly or disassembly. Prior Basepad extensions having an openable bottom end may require the separation of multiple parts that can be dropped, misplaced, or lost.